The Savage 110 ML is the only muzzloading rifle that I am aware of that is rated for smokeless powder. It has some kind of special vent to prevent a pressure spike from blowing up the gun.

Considering how much zip you can get with three 50 grain Pyrodex pellets, I never have really considered purchasing the Savage. Back in my early days of in-line muzzleloading, I experimented a bit with smokeless load in a KnightRifle. I now know just how hazardous this could have been . . . but the only thing I really learned was that the extra heat and pressure made it difficult to get sabot loads up to even the same speedas 150 grains of pellets without accuracy problems. The only loads that really worked for me with smokeless were lead conicals at around 1600 fps.

I have since been enlightened as to the hazards of smokeless powder. Please don't even try it in an Encore. It could hurt you.